Keep this equation in mind:

         Wattage (watts) = Voltage (volts) * Current (amps).

So, 1200 watts on the AC (plug) side of the inverter:

         1200 = 120V * 10A.

and on the DC side of the inverter (your van):

         1200 = 12V * 100A

That means that to get your 1200 watts of power for your 120V appliance,
you need to draw one hundred amps from your battery.

NOTE TO THE PURISTS: Yes, I know I'm using ballpark figures and
oversimplifying things a lot, and I'm ignoring any power losses in the
inverter. I'm just trying to make the point that the current you are using
on the AC side of tine inverter is going to draw *at least* ten times as
much on the DC side.

Tim

At 09:48 PM 10/9/2006 -0700, Mark C wrote:
>So I guess my Wagan outsmokes your Coleman.. I guess Coleman must use
>cheaper chinamen... cause the Wagan is only 700 watts... and I seem to
>remember printing close to 50 checks one time... but you are making me
>think my replacement inverter will need more than 1200 watts rating...
>
>
>From: Mark Evans <markimus@GMAIL.COM>
>To: vanagon@GERRY.VANAGON.COM
>Subject: Re: Printing w HP1020 off a Deep Cycle Battery
>
> > I use the Coleman 1200 Watt PowerMate from GoWesty.
> >
> > Mark
> >
> > On Oct 9, 2006, at 6:59 PM, Greg Potts wrote:
> >
> > > Hi Mark,
> > >
> > > What rating was your inverter?
> > >
> > > </Greg>
> > >
> > > On 9-Oct-06, at 4:52 PM, Mark Evans wrote:
> > >
> > >> I just hooked up my Laserjet 1022 (mac version) in my Van and it blew
> > >> the fuse in my inverter after a print job of 30 pages.
> > >
> >
>
>----- End Original Message -----